Telephone-transmission system



June 24'?, 1924. f 'gZ w. H. BENDERNAGEL .TELEPHONE TRANSMISSION SYSTEMPatented June 24, 1924.

UNTQ STATES PATENT OFFICE.

'WILLIAM H. BENDERNAGEL, OF QUEENS, NEW YORK, ASSGNOR .TO-WESTERN ELEC.-

TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A COBPORATI/ONy OF NEW"l YORK.

TELEPHONE-TRANSMISSTON SYSTEM.

Application led December 16, 1919, Serial No; 345,250.

T 0 all wlw/m 25, may concern.'

Be it known that I, WILLIAM H. RENDER- NAGEL, a citizen of the UnitedStates, re-' siding at Queens, in the county of Queens,

v State of New York, have invented certain new and useful Improvementsin Telephone- Transmission Systems, yof which the following is a full,clear, concise, and exact description. y

This invention relates to telephone transmission systems, and moreparticularly to such systems in which repeaters are employed. The objectof the invention is to economize in equipment byV providing mea-nswhereby several'conversatlons may be amwhich shall be common tol aplurality of op-l Another fea' eratorscord or link circuits. ture is toprovide for using a single repeater equipment for a plurality of cord orlink circuits so that the repeater may be associatedwith said circuitsin lsuch a'manner that conversations may be carried'on simultaneouslyover all'pairs of'linesv joined by the cord circuits. Another .featureis to render the repeater operativeonly when at least a single cordcircuit is connected to two subscribers lines. Another feature is toprovide signals and to provide a distributor which is rendered operativeat the proper times. Other features and advantages of the inventionwillbe obvious as the description proceeds.

The invention will be understood from the description in connection withthe drawing which shows a repeater equipment consisting of two one-wayamplifiers connected to a distributor which in turn is connected to acord circuit.

In the drawing reference characters A and B designate subscribers7 linecircuits which are provided with the usual equipment such as linesignal, signal relay, telephone set, jack, etc. When the subscriber Y atA removeshis telephone from the hook,

the relay 2 is energized, thereby closing a circuit through the linelamp L.

Upon noticing the line signal at L, the operator inserts her plug Pintojack J. This energizes the cut-off relay l, thereby extinguishing,light L and at, the same time lights the light L and energizesj therelay 3 byv a circuit which can be traced froml ground throughrelay 1sleeve contacts of jack? J and plug P, lamp L, relay 3 and battery toground. The insertion of plug Pin jack J simultaneously closes a circuitfrom battery, upper half of left-hand wind` ing ofl transformer T,"tipcontacts of plug' and jaclgsubscribers set, ring contacts of jack andplug, relay il, lower half of lefthandV winding vof'transformer T, backto battery. This energizes relay 4,' thus clos-' ing its contactand'extinguishing light L', but maintaining relay 3 eneregized.'v

The relay 3u`pon energization closes its leftehand and right-handcontacts thereby starting the motor M through the circuit which may betraced from ground, left-hand contact of' relay 3, motor IM, battery toground. The closing of the right-hand contact of relay closes a circuitthere through.' and through the leftdiand winding ofmarginal'relay`3-and battery to'ground.' The motor M drives the' brushes of thedistributor in a manner whichwillno-wbe eX- plained.

The distributor shown in theV lower part of the figure consists of anumber of sectors S1, S2, S3, etc., insulated from each other and eachsector containing. a number ofsegmen'ts, s1, s3, S5, which are alsoinsu` lated from each' other. tors into which the distributor is dividedis equal to twice the number of cord circuits for which it is designedto be usedas more fully explained below. Thus, sectors S1, and S, belongtof one cord circuit, sectors S2 and Sl'f, to a secondcord circuit, etc.On the face ofthe distributor are disposed eight concentric rings011,93, r3, etc. For'connecting the repeater inthe various cord circuitsin accordance with the various positions of the arms a, two rigidly*connected arms a and a are mounted at the center of the distributor andare driven at a very high speed, say 4,000 revolutions per minute, foreX- ample, by the motor M, whose shaft m is connected to the axis of thearms ce, a', by connections not shownv on the drawing. The arms a, a,are provided with a number of brushes b1, b2, b3, etc., which areinsulated from each other, and serve to momentarilyV connect thevarioussegments s1, s2, s3, tothe rings r1, r2, r3, etc., while the arms arere- The number. of secy lio ,infissi-.Wm

volving, as will be obvious from the draw ing. The terminals of therepeater equipn ment are connected to the eight rings of the distributoras shown. The right and lefthand windings of the transformers T and T'respectively and the terminals of the balancer nets N and N' of a singlecord circuit are connected to the segments 81, s2, s3, etc., of anopposing pair of sectors S, while similar terminals of each cord circuitare connected to the other pairs of opposing sectors of the distributor.

When the operator inserts the plug P' into the jack J', the cut-ofirelay1' is energized as is also the right-hand winding of relay 3' through acircuit from ground, relay 1', sleeve contacts of jack and plug, lampL', right-hand winding of relay 3', battery to ground. The current nowpassing through the two windings 0f relay 3' energizes it sufficientlyto close its contact, thus completing the circuit from ground, throughbattery, oontact of relay 3', wire 21, and the filaments of repeaters Rand R' to ground, thus rendering the repeaters operative.

When the subscriber B removes his receiver from the hook, a circuit iscompleted from battery through the upper right-hand winding oftransformer T', tip contacts of plug P', andA jack J', subscribers set,ring contacts of jack and plug, relay 4', lower half of right-handwinding of transformer T', back to battery. This energizes relay 4 andshort-circuits lamp L'l, thereby extinguishing the same. It is thus seenthat the insertion of plug P into jack J starts the distributor arm torevolving and that the insertion of both plugs of a cord circuit intojacks renders the repeater bulbs operative and that either subscriber Aor B may signal the operator through lamps Ll or L'1 by moving theirhooks up and down, since such an operation deenergizes and energizes therelays 4 and t' respectively, thus short-circuiting Vthe lamps Ll andL'1 respectively, and removing the short circuits therefrom.

`With the plugs in the jacks, either subscriber can be rung by operatingthe ringing keys A and K' in the usual way. lNit-h the receivers off thehooks, voice transmission will be amplified by passing through theamplifier equipment as follows: Voice currents from subscriber A throughhis equipment, the. tip and ring contacts of j ack J and plug P, relay4E and left-hand winding of transformer T, where it is transferred t0the right-hand winding of transformer T and passes through wire 5 tosegment s1 (while arms a, a' are in proper position) through brush l,ring r1, wire 6, condensers and primary of transformer t, wire 7, ringr, brush .7)7, wire v8, balancer N, wire 9, segcirculateV ment S5, brushb5, wire 10, condensers and primary winding of transformer t, wire 11,ring r3, brush 3, segment s3, Wire 12 to the right-hand winding oftransformer T. At transformer t, the voice current is transformed to thesecondary of transformer t where it circulates through the input circuitof repeater R and is amplified and passes to the output circuit ofrepeater R to the transformer t1, from whence it divides, one f halfpassing through wire 13, ring rg, brush 228, wire 14, balancer N', wire15, segment s6, brush 5G, ring r6, wire 16, condensers, transformer t1,to ground, and the other half passing through wire 20, ring r2 brushZ22, segment s2, lead 19, left-hand winding of transformer T, lead 18,segment s4, brush b4, ring r, lead 17, condensers and primary winding oftransformer t, to ground. At transformer T' the current is transformedto the right-hand winding and passes through the tip and ring contactsof plug P' and jack J' to the telephone set of subscriber B. Voicecurrents from subscriber B will be amplified in exactly the i samemanner except that they will pass through the bulb B', instead of thebulb R.

Only one cord circuit with its connections is shown in the drawing. Ttwill be obvious that duplicate cord circuits will have the contacts oftheir relays corresponding to relay 3 connected in parallel to the motorM and the contacts of their relays corresponding to marginal relay 3'will likewise be connected in parallel to the wirel 21 for energizingrepeater filaments whenever the two plugs of any cord circuit connectany two subscribers line circuits.

The connections R1, R1', R11 and R11' operate as a filter in the wellknown way as illustrated for example in the patent to Gr. A. CampbellNo. 1,227,114, May 22, 1917, to prevent disturbances caused by the makeand break contacts of the distributor brushes from reaching theamplifiers, but at the same time permitting the high frequency voicecurrents to be amplified. The network N balances the line circuit ofsubscriber A and the filter R1' balances the filter B1 with respect tothe repeater. Similarly the network N1 balances the line. circuit ofsubscriber B and the filter R1, balances the filter R11'. The connectionis maintained between the repeater equipment and any individual cordcircuit only a fraction of the time. For example, with an eightcordcircuit distributor, each cord circuit will be connected to theamplifier one-eighth of the time. The arm a, a' will be driven by themotor M sufiiciently rapid so that about fifty or more contacts will bemade per second in order that in effect, continuous transmission foreach set of subscribers will be IGH maintained, and will be amplified aproportionate amount by the amplifier 1i, R. In this way, a singlerepeater equipment is available for a plurality of cord circuits and maybe used simultaneously with j all of them without cross-talk, thussaving a duplication of amplifying equipment.

Any given link circuit is alternately in the closed condition and theopen condition, each open period being about fifteen 'times as long aseach closed period, since the distributer after closing one link circuitmust open that circuit and closeseven other circuits in successionbefore again closing the one circuit. Transient currents occur of courseat the make and at the break. Thus, during each period when thedistributer brushes are not touching the contacts in a given cordcircuit the current in that circuit varies from the current which wouldflow were the circuit not subject to interruptions. This variation,appearing once at every revolution of the distributer or at a frequencyof 6632,- cycles per second where the distributer makes 4000 revolutionsper minute, tends to produce a low frequency wave of current in thecircuit. Such a wave tends to produce a low tone in the receiver.Therefore, the filters R, B-l, R11, R11 are inserted in the circuit forthe purpose of preventing as far as is feasible the appearance of such acurrent wave. Of course, the design of these filters must be such thatthey will not unduly interfere with t-he passage of the waves of currentcorresponding to the voice waves of sound. rThe filters may be designedin accordance with the princi-ples set forth in the Campbell patentreferred to above, and may be of any suitable type, the specific form ofthe filter being no part ,of the present invention.

What is claimed is:

l. In a telephone system, a plurality of subscribers line circuitsterminating at a central switchboard, a plurality of link circuits, arepeater, means whereby said repeater may be connected in said linkcircuits in rapid succession, and means for rendering said repeateroperative when any one of said link circuits is connected to any two ofsaid subscribers lines.

2. In a telephone system, a plurality of subscribers line circuitsterminating at a central switchboard, a plurality of link circuits, arepeater, a. distributor for connecting said repeater in said linkcircuits in rapid succession and means for rendering said repeateroperative when any one of said link circuits is connected to any two ofsaid subscribers lines.

3. Tn a telephone system, a plurality of subscribers line circuitsterminating at a central switchboard, a plurality of link circuits, arepeater, a distributor having a revoluble arm, for connectingsaid'repeater. in said link circuits in rapid succession, means forrevolving said arm when a'call initiated by any one of saidsubscribersis answered by an operator, and means forv rendering saidrepeater operative fwhenany one of said link circuits is connected toranf two of saidsubscribers lines. f f 4. InV a telephone system, aiplurality lvof subscribers line circuits terminating at a centralswitchboard,'a plurality of. link circuits, a repeater, and adistributor for con'- necting said repeater in said link circuits atsufficient frequency to produce a low tone, and means for filtering outthe distributor make and break disturbances before they reach saidrepeater. v

5. In a telep-hone system, a plurality of subscribers line circuitsterminating .at a

-central switchboard, a plurality of link circuits, a repeater, and adistributor for connecting said repeater in said link circuits at a lowfrequency within the range of hearing, and means for filtering out thedistributor make and break disturbances before they reach said repeater,without interfering with voice transmission.

6. In a telephone system, a plurality of subscribers line circuitsterminating at a central switchboard, a plurality of link circuits, arepeater equipment consisting of two one-way amplifiers, and means forconnecting said repeater into and disconnecting it from each of saidlink circuits at such a frequency that the interruptions do notseriously affect the intelligibility of conversation being transmittedthrough said link circuits, and maintaining said repeater connected ineach link circ-uit for substantially equal intervals of time.

In a telephone system, a plurality of subscribers line circuitsterminating at a central switchboard, a plurality of link cir cuits, arepeater equipment consisting of two one-way amplifiers, means forconnecting said repeater into and disconnecting it from each of saidlink circuits at suchV a frequency that the interruptions do notappreciably affect the intelligibility of conversation being transmittedthrough said link circuits, and maintaining said repeaterconnected ineach link circuit for substantially equal intervals of time,pand meansto prevent the disturbances caused by said make and break connectionsfrom reaching said repeater.

8. A telephone system comprising a plurality of transmission lines, anamplifier common to said lines, balancing networks corresponding to saidlines, and means for connecting said amplifier in operative relation tosaid lines and corresponding networks in rapid succession.

9. A telephone system comprising a plurality of transmission lines, anamplifier common to said lines, balancing networks corresponding to saidlines, and means Jfor momentarily connecting said amplifier in operativerelation to each of said lines and the corresponding networks atsuciently close intervals to provide for intelligible speechtransmission over said transmission lines.

10. A telephone system comprising a pilurality of transmission lines, anamplifier common to said lines, means for connecting said amplifier inrapid succession with said transmission lines, and means renderedoperative' when any of said transmission lines are taken for use forrendering said connecting` means active.

1l. A telephone system comprisingl a plurality of transmission lines, anamplifier common to said lines, means for connecting incassa saidamplifier With said transmission lines, and means rendered operativewhen any of said lines are in use for rendering said connecting meansactive and for rendering said amplifier active.-

l2. A. plurality of. lines, a repeater comprising a unidirectionalcurrent transmitting amplifying element having an input circuit and anoutput circuit, and means comprising a rotary commutator for effectivelyconnecting said out-put circuit to dit- 'erent ones of said lines inrapid succession and for also effectively connecting Said input circuitto different ones of said lines in rapid succession.

In Witness whereof, I hereunto subscribe my name this 12th day ofDecember, A. D.

XILLIAM H. BENDERNAGEL.

